MU metal foil

[Leevi]

I have had several time issues where the power transformer causes hum via reverb tank.


Has anyone tried MU metal shields for protection and how the protection should be done?


/Leevi

[shooter]

I searched "metal shielding" here and got this, you can read it, lunch is ready 


https://el34world.com/Forum/index.php?action=search2

[Latole]

I have no try this. The only amp I have to repair with this issue, I just move a bit reverb tank and no more hum.
Which amp did you talking about ?

 What is MU? Multi Usage metal tape ? Kind of air duct tape ?
Transformer is already in a grounded steel case

[Latole]

I searched "metal shielding" here and got this, you can read it, lunch is ready 


https://el34world.com/Forum/index.php?action=search2

Not post there, noting

[Leevi]

I have no try this. The only amp I have to repair with this issue, I just move a bit reverb tank and no more hum.
Which amp did you talking about ?

 What is MU? Multi Usage metal tape ? Kind of air duct tape ?
Transformer is already in a grounded steel case

The magnetic field of the PT causes the hum and if there is no room to move the tank in the  cabinet the only way is to protect the tank (or PT). Normally it helps a bit if the tank output is placed in the other end as the PT. I see this as a more general issue especially in heads.

https://en.m.wikipedia.org/wiki/Mu-metal

/Leevi

[Williamblake]

I had the same issue abd put a 2mm metal plate between transformer and tank, that solved it. The plate had to be screwed on tight or it would rattle like hell. I dont think foil will help.

[tubeswell]

Foil made from MU metal will be about as useful as tinfoil hats

[shooter]

 


I scraped out the last of my Mu metal shims we used in MR, ~ 30lbs.  I told the scrapper "It's Mu metal, do I get a better price";  He replied "If you want it to be my metal, stick it in the iron pile, n that's what I'm paying"
ah well, one last thing to trip over.

[Leevi]

I had the same issue abd put a 2mm metal plate between transformer and tank, that solved it. The plate had to be screwed on tight or it would rattle like hell. I dont think foil will help.

I have tried using  different metals like, steel, aluminium, copper etc. but not that thick material.

The magnetic field can be protected by using  MU metal, sometimes with steel but it probably depends on its composition?

BTW. I have learned that never use toroidal PT if you have a reverb in your amp.

I scraped out the last of my Mu metal shims we used in MR, ~ 30lbs.  I told the scrapper "It's Mu metal, do I get a better price";  He replied "If you want it to be my metal, stick it in the iron pile, n that's what I'm paying"ah well, one last thing to trip over.

MU metal is damn expensive

/Leevi

[shooter]

MU metal is damn expensive

ya, the box cost $1,000's in the '90's, but time moved on, and the 'ol guy I sell to only has so many piles